The invention relates to a method and apparatus for feedback-controlling ignition timing so that the ratio of the amount of fuel consumption to output torque, i.e. a fuel efficiency, is maximized.
Conventionally, ignition timing in an internal combustion engine is controlled by using a centrifugal advance device to make the ignition timing advance with respect to the engine speed and a diaphragm advance device to make the ignition timing advance with respect to an intake air pipe negative pressure.
The fuel efficiency of an internal combustion engine depends largely on ignition timing. In conventional control systems, it is impossible to control the ignition timing accurately over the entire range of the engine operating conditions so as to maximize the fuel efficiency, and this makes the fuel efficiency poor.